Relationship between Urbanization and Heavy Metal Pollution in Soils in Shanghai Suburb
上海城郊地区城市化进程与农用土壤重金属污染的关系研究

The process of urbanization has promoted economic development and social progress, but it has also caused a series of problems, especially the problem of urban ecological environment. Therefore, the research into the relationship between urbanization and the urban ecological environment is of great significance and has already been touched in many other researches. Heavy metal contamination of soil is an important topic in soil environment and the relationship between urbanization and the distribution of heavy metal in suburban soils varies in different regions and different phases of urbanization. However, the correlation between the degree of contamination and the level of urbanization process has not been discussed in details. In this research, the pollution in suburban districts of Shanghai is investigated as the case study. Based on the data collected from various authorized sources (Shanghai Statistical Yearbook, Shanghai Statistical Bulletin, General Detailed Soil Survey of Shanghai), the correlation of urbanization and the contamination of heavy metal in suburban soils is analyzed by using Correlation Analysis and Regression Analysis Methods, before which, the comprehensive index of urbanization and heavy metal pollution index of agricultural soil in suburban district of Shanghai are achieved. Moreover, the distribution differences of heavy metal elements in different regions and the influencing factors are explored so as to provide theoretical support for the coordination of urban development, the rational utilization of soil and soil environmental protection. The results show that: 1) There are obvious disparities in the urbanization levels of suburban areas in Shanghai, and the urbanization level of the suburbs is higher than that of the outer suburbs in Shanghai; The accumulation degrees of heavy metal vary in different districts with the sequence in accumulative degrees as follows: Zn >Cu> Cr> Pb; 2) The results of Correlation Analysis show that the single-factor pollution indices of Zn and Cu as well as the integrated pollution index of heavy metals are positively correlated with the level of urbanization, while the correlation of single-factor pollution indices of Pb and Cr with index of urbanization level is not obvious; 3) The results of Regression Analysis show that the fitting curves of the three indices (Zn single-factor pollution index, Cn single-factor pollution Index, and the integrated pollution index) and the comprehensive level index of urbanization demonstrate the typical features of EKC. All the suburban areas except Min-hang District do not cross the inflection point, staying on the left side of the EKC curve.